c): restart a service provider, if same numbers come back, restart the other.

If you know AfwApplogViewer use the ListSynchronizingLogs, ListSyncDetails, etc operations to lead you further to which log(s) are your troublemakers. Verify sane config (Consistency Check), contents (bad data in log), etc. Restart the log, ultimately delete and recreate log. Data can be restored from a backup or the redundant peer (Log Config->Status tab or via AdvHtArchiveTool.exe, just copy THAT log file to an empty folder and use Insert Data To Logs. Object GUID must be same for tool to work. Log files have GUID in their names to point you to the correct file).